Currently, a liquid crystal display device including a liquid crystal panel is widely used in various kinds of electronic apparatuses such as a mobile phone, a personal computer, and a music player. The liquid crystal display device includes (i) a liquid crystal panel in which liquid crystal cells are arranged in a matrix manner and (ii) a driving circuit for driving the liquid crystal panel. The liquid crystal display device displays an image by adjusting optical transmittance of liquid crystal by utilizing an electric field.
Specifically, the liquid crystal panel includes (i) a plurality of gate lines, (ii) a plurality of source lines, (iii) thin film transistors (TFTs) which are provided at respective intersections of the plurality of gate lines and the plurality of source lines, and (iv) liquid crystal cells connected with the respective TFTs so as to constitute respective pixels. Each of the TFTs has (i) a gate electrode connected with any one of the plurality of gate lines and (ii) a source electrode connected with any one of the plurality of source lines so that a pixel voltage signal is supplied to a liquid crystal cell via a source line in response to a scan signal supplied via a gate line. Each of the liquid crystal cells has a pixel electrode connected with a drain electrode of the TFT and a common electrode that faces the pixel electrode via liquid crystal. In the liquid crystal cell, the liquid crystal is driven in response to a pixel voltage signal supplied to the pixel electrode, and optical transmittance of the liquid crystal is thereby adjusted.
Typically, all the source lines provided in the liquid crystal panel are simultaneously driven during one (1) horizontal scanning period. On the other hand, a method is known in which the source lines are driven in a time division manner during one (1) horizontal scanning period. Such a method is disclosed in, for example, Patent Literature 1.
In recent years, electronic apparatuses are rapidly increased, each of which includes the liquid crystal display device with a touch panel. According to such an electronic apparatus, an input operation with respect to the electronic apparatus is carried out by pressing any of various operation buttons, which are displayed on a display screen, with a finger, a pen, or the like, instead of carrying out an input operation with the use of a conventional user interface such as a keyboard or buttons.
A capacitance type touch panel, which operates in one of operation principles of touch panel, operates by detecting a change of a sensor which change has been caused by electrostatic capacitance of a finger of human. However, in a case where a noise is caused while sensing, the noise will be detected. This leads to a decrease in recognizing performance of the touch panel.
Such a noise is generated when, for example, a liquid crystal module is driven which is provided on the back of the touch panel (hereinafter, such a noise is referred to as “liquid crystal drive noise”). In order to reduce or avoid the liquid crystal drive noise, the following measures have been taken, that is, for example, (i) a gap between the liquid crystal module and the touch panel is widened or (ii) a shield layer is provided between the liquid crystal module and the touch panel.